Equations of straight lines Mathematics resources（直线方程的数学资源）.pdf

Equations of straight lines mc-TY-strtlines-2009-1 In this unit we find the equation of a straight line, when we are given some information about the line. The information could be the value of its gradient, together with the co-ordinates of a point on the line. Alternatively, the information might be the co-ordinates of two different points on the line. There are several different ways of expressing the final equation, and some are more general than others. In order to master the techniques explained here it is vital that you undertake plenty of practice exercises so that they become second nature. After reading this text, and/or viewing the video tutorial on this topic, you should be able to: • find the equation of a straight line, given its gradient and its intercept on the y-axis; • find the equation of a straight line, given its gradient and one point lying on it; • find the equation of a straight line given two points lying on it; • give the equation of a straight line in either of the forms y = mx + c or ax + by + c = 0. Contents 1. Introduction 2 2. The equation of a line through the origin with a given gradient 2 3. The y-intercept of a line 4 4. The equation of a straight line with a given gradient, passing 7 through a given point 5. The equation of a straight line through two given points 8 6. The most general equation of a straight line 10 c www.mathcentre.ac.uk 1